They are usually baked in paper cups in a muffin tray. Not sure if you have them in your country so here's a picture:
And a recipe from Martha Stewart:Devil's Food Cupcakes
3 ounces unsweetened chocolate, chopped
1 teaspoon baking soda
1/2 cup boiling water
1 cupunsalted butter, room temperature
2 cups sugar
5 large eggs
3 cups all-purpose flour
3/4 cup buttermilk
1 teaspoon pure vanilla extract
Heat the oven to 350°F. Line the bottom of two 12-cup muffin tins with paper liners.
Melt chocolate in a double boiler over simmering water. In a bowl, stir baking soda into the boiling water; stir this mixture into chocolate. Set aside to cool slightly.
Using an electric mixer, cream butter and sugar until the mixture is light and pale yellow in color. Add eggs, one at a time, and continue to mix until thoroughly incorporated. Add flour and buttermilk, alternating between small amounts of each, and blend well.
Add the melted chocolate and vanilla to the batter, and stir well. Pour the batter into the paper cups, and bake until a cake tester comes out clean when inserted into the center of a cupcake, about 30 minutes. Remove cupcakes from the oven, and allow them to cool briefly in the muffin tin before removing them to a wire rack to cool completely. Ice, and serve.